- Appearance? Take off the hood and look closely for: rust or corrosion (especially around joints, bolt heads, etc), any evidence of overheating (like discolored or flaked off paint, browning on any plastic parts, warping), leaks (water stains, mineral deposits).

- Give it a test. Make sure the seller has not cranked it recently so the motor is stone cold. Does it crank on the first or second pull? Any smoke? If yes, what color and how much? Do you see a good stream of water from the pee hole?

- You say used only 2-3 years but is that also the age of the motor or has it sat in storage for some time?

Not sure about prices in Europe, what with VAT and such but in the USA I think with a little shopping you could find a similar engine for less. With a little luck possibly a lot less.

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The water is always bluer on the other side of the ocean.

EUR 650 for 3 y.o. 6hp Merc is a rip off. Unless you are bet sure this engine is immaculate. Note most small outboard users are complete ignorant when it comes to outboardmaintenance and service. Esp. so in the Med.

Haggle. And make sure the engine is fine. Many are not. (I would buy a new one).